The continuing explosive growth in telecommunications traffic has led to the development of various techniques for providing users with telecommunications service and charging for it. In order to provide large increases in network capacity, technologies such as Asynchronous Transfer Mode (ATM) and their associated communications protocols are now being widely deployed. To provide flexibility and thus optimal use of this increased capacity, the telecommunications traffic carried over an ATM link may itself be coordinated and managed by the use in a layered manner of several additional protocols. For example, data for a World Wide Web page being transferred at the application level from a server to a client/user in accordance with the Hypertext Transfer Protocol (HTTP) may be embedded in packets managed in accordance with the Transmission Control Protocol and the Internet Protocol (TCP/IP). The packets in turn may be embedded in Point-to-Point Protocol (PPP) packets, which are themselves divided among ATM cells carried over the ATM transport layer.
Although this multiple layering or stacking of protocols provides great flexibility and facilitates the implementation of new techniques, it does pose additional challenges, for example in the generation of Service Detail Records. A Service Detail Record (SDR) is a record that summarizes the traffic carried on a monitored communications link (for example the identity of the nodes at each end of a TCP/IP connection, the duration of the connection and the total volume of data transferred over that connection). An SDR can be assembled for each of the layers in the communications stack.
Prior approaches to gathering statistics on the performance of various layers in a communications stack have included:    Using an MIB (Managed Information Base), in which summary performance statistics for various parameters (e.g. number of cells or number of errored cells) are kept as separate attributes of the MIB. Although an MIB can keep statistics on many levels in the communications stack, it cannot keep track of the relationships between the individual attributes. Thus it may keep track of the active virtual circuits (VCs) and of the IP connections, but it does not maintain any reference between the two.    Monitoring IP “flows”: “netflow” records have been defined that provide summary statistics for each IP flow that is detected by an IP network device. Because these records are produced by devices that typically operate at layer 3 in the standard ISO seven-layer protocol model, they report solely on the IP level. They do not therefore provide any information relating to other layers in the protocol stack.
It is an object of this invention to provide a method and apparatus which facilitate the use of Service Detail Records in a system using layered protocols.